Water storage tank in basement

[Bill Sargeson]

I wanted to see what you all thought of this.  It might be no big deal but I haven't come across this before....looking at this house for a buy and hold and in the basement(basements are rare in this part of NC) sits a large water storage tank with a pump.  I thought to myself this house must be on a well, I called the city and they said no, it is hooked up to the city water and sewer.  Any idea why it would be there?  The utilities are off right now so I couldn't check if everything is working.  I just don't see the point of it...any thoughts?